Friday, November 20, 2015

Bypass roof fan control

In the bathroom there's an exhaust fan so can vent unpleasant odors, and also any steam from taking a shower. The fan I have slows down after some time running, doesn't matter if it's pushng air out, or pulling air in, still exhibits same behaviors.

As part of troubleshooting, plus I was convinced it was the problem, decided to bypass the control board. The control board is simple in that there's just a knob which changes voltage sent to the motor. My theory is that the control board could've been faulty to a degree in that it slowed the motor down over time.

Before modification

This is actually a fairly simple thing, but be warned for a couple reasons.

This will likely invalidate any warranty remaining on fan.

Messing around with 12V DC electricity, so be vewy vewy careful

Other bad things could happen working with electricity

Am fairly comfortable around electricity so this was a breeze. Upon examination, there's a red and black wire (fairly thick) coming into the control board. Leaving the control board there are two wires going to a switch. Leaving the switch is two wires going to the fan. It seems that the switch controls which direction the electricity is sent to the motor, which in turn controls which was the air blows.

Quick test

First step was to snip the wires leaving the control board, followed by snipping wires coming into control board. Did it this way to lessen the amount of time the live wires were not connected to anything. As part of this I also stripped the wires with my lineman pliers.

All safe and snug

As a quick test in which way to connect the wires, and to validate it would work, twisted them together like so and hit the wall switch that controls the fan (different from switch on the fan housing that controls the direction). Lo and behold it works great.

Once did this quick verification I then quickly tied them together like so. Just some wire nuts leftover from a ceiling fan installation from someplace, probably my house. I say ceiling fan as those type of wire nuts generally come from packaged goods.

As the fan is still working this modification didn't harm it in any way that I can tell. However, it didn't solve the problem so there must be something else wrong. The fan still slows down after a certain amount of time.

I think the next step is to validate voltage going into the switch, and it leaving the switch. The other thing I think it could be is the motor itself if all the voltages check out. There's also a possibility that the voltage being supplied dwindles over time. I would find that hard to believe but anythings possible at this point. The wall switch could also be causing the problem.

Will create another entry when get around to this again. First have to install water heater and fix the shower pan. Big hole in shower pan..... Am Pepe Le Pew now.